Introduction to the 990-08-50-01-CN Vibration Transmitter
When a rotating machine begins to vibrate excessively, the resulting damage can halt production and require costly repairs. The 990-08-50-01-CN from Bently Nevada provides a direct solution by converting shaft vibration into a standard 4-20 mA signal. This two-wire transmitter is designed for continuous monitoring in industrial environments, helping maintenance teams detect problems early.
Part of the 990 series, this unit accepts one non-contacting 3300 NSv Proximity Probe and extension cable. It delivers a 4-20 mAdc output over its full-scale range, which is set to 0-8 mils pp (0-200 μm pp) for this configuration. The transmitter operates from a +12 to +35 Vdc input, making it flexible for various control systems.
Key Features and Technical Specifications
The 990-08-50-01-CN is engineered for accuracy and reliability. Its 4-20 mA loop accuracy is within ±1.5% over the specified full-scale range, measured from the TEST signal input to the voltage across a 250 Ω loop resistance. This error is in addition to the Prox Out Incremental Scale Factor, ensuring precise vibration data.
- Full-scale range: 0-8 mils pp (0-200 μm pp)
- System length: 5.0 meters (16.4 feet)
- Mounting: 35 mm DIN rail clips
- Input: Accepts 1 non-contacting 3300 NSv Proximity Probe and extension cable
- Power: +12 to +35 Vdc input at the transmitter terminal
- Maximum loop resistance: 1,000 Ω including cable at 35 Vdc
- Current limiting: 23 mA typical
- Frequency response: 5 Hz to 6,000 Hz +0, 3 dB
- Minimum target size: 9.5 mm (0.375 in) diameter
- Leadwire length: Maximum 3 meters (10 feet) for Proximitor Sensor Output (BNC connector)
One distinctive feature is the NOT OK/signal defeat function. If a fault condition occurs, the signal output drops to less than 3.6 mA within 100 µs. Once the condition is cleared, the output restores within 2-3 seconds. This fast response protects downstream equipment from false readings.
Real-World Applications
In a typical scenario, a plant engineer monitors a critical pump that operates near its design limits. The 990-08-50-01-CN provides continuous vibration data, allowing the team to spot increasing trends before a bearing fails. This proactive approach reduces unplanned downtime and extends equipment life.
The transmitter is suitable for machinery such as fans, motors, and compressors where shaft vibration is a key health indicator. Its 4-20 mA output integrates easily with PLCs, DCSs, and SCADA systems, simplifying installation into existing monitoring architectures.
Installation and Setup
Mounting the 990-08-50-01-CN is straightforward with the included 35 mm DIN rail clips. The probe must be gapped between 0.5 and 1.75 mm (20 and 55 mils) from the target to ensure full-scale range. This gap is critical for accurate readings, so follow the manufacturer's guidelines during setup.
Power is applied at the transmitter terminal with +12 to +35 Vdc. The loop resistance must not exceed 1,000 Ω at 35 Vdc, including cable resistance. For non-hazardous, Zone 2, or Div 2 hazardous areas, the power supply is rated at 28 V. Ensure all connections are secure and the probe cable length stays within the 3-meter limit for the BNC output.
Maintenance and Reliability
Regular inspection of the probe gap and cable integrity is recommended to maintain measurement accuracy. Because the transmitter uses non-interacting external zero and span adjustments, calibration is simple and does not require disassembly. Periodically verify the loop current against a known vibration source to confirm performance.
The device is built for long service life in industrial settings. Its current limiting at 23 mA typical protects the loop from overcurrent conditions. With proper care, the 990-08-50-01-CN delivers dependable vibration monitoring for years.
Compatibility and Integration
The 990-08-50-01-CN accepts a single 3300 NSv Proximity Probe, which is a standard in the industry. Its 4-20 mA output is universally compatible with most control systems, eliminating the need for specialized interfaces. The 5.0-meter system length provides flexibility in mounting locations.
For hazardous area installations, the CN agency approval option ensures compliance with country-specific requirements. Always verify that the transmitter's power supply matches your facility's voltage and that the loop resistance is within limits.
Support and Availability
The 990-08-50-01-CN is available through AutoDCSTech, a trusted supplier of industrial automation parts. In stock and ready to ship, this transmitter can be ordered with confidence. For technical questions or lifecycle status, contact AutoDCSTech for prompt assistance.
